The first symbol that comes to mind is the peace/"ban the bomb" sign. I've always liked it and identfied with it for many years. However, growing older, I'm not as undivided about it anymore. I found out there may be meanings behind it that I cannot support, so stopped wearing the symbol a long time ago. I will always have a weakness for it though, since it will always be a symbol for my younger years when I was still a naive, second generation hippie.
I'm also drawn to celtic knots and symbols. I'm not sure if that is past life-related, ancestry-related or both. However, I had a chilling experience once that leads me to believe that there may be more to it than just my bloodline. I don't know if anyone remembers, but three years ago Irish singer Dolores O'Riordan passed away, she was very dear to our heart. We couldn't go to Ireland to be there for her wake, but we were able to follow her funeral live on Limerick's local radio station. At the end of the mass bagpipes started to play, and I got massive chills throughout my entire body. Not so strange of course, given the circumstances, but it wasn't just that. I felt this strong, almost atavistic urge to stand up straight, take off my (non-existent) hat and salute. The entire experience was loaded with chilling energy, I don't think I've ever experienced anything like that before.
The Christian cross and dove are also symbols that hold a special place in my heart, for obvious reasons.
I'm saving this one for last as I'm not sure if it counts as a symbol, but cats. Cats pictured anywhere, cats mentioned in songs, and obviously real cats, they always stike a very deep and special chord with me.